The purpose of this interventional sham-controlled pilot study is to study the effects of using portable air cleaners (PACs) in outpatient adults with prediabetes. The primary aims are to determine the effect PAC's have on glycemic variability and the concentrations of circulating biomarkers of inflammation.

Inclusion Criteria:

• Participant is ≥18 years old
• Participant and members of household are reported to be non-smokers (defined as no household members are currently known to smoke cigarettes or use other tobacco products including e-cigarettes)
• Participant is to understand/speak English or Spanish
• Participant can understand study procedures and give informed consent
• Participant has prediabetes, defined as the absence of diabetes and any of the following: fasting plasma glucose 100-125 mg/dL, 2 hour plasma glucose of 140-199 mg/dL after 75 g oral glucose tolerance test, or A1c 5.7- 6.4%.
• Able to wear CGM for 2 two-week periods
• Able to participate in telephone or video conference for home equipment setup if needed
• Able to visit clinic for blood draws before and after the study period
• Do not intend to sleep anywhere outside of primary bedroom for more than 48 consecutive hours or a total of 7 days during the study period.
• Ability to lift, or access to assistance with lifting, 20 lb to set up air filter appliance in bedroom.
• Have not undergone major dietary change (such as change from usual diet to intermittent fasting or caloric restriction) in the past 2 weeks, and do not intend to during the study period

Exclusion Criteria:

• Participants who have diagnosed diabetes, or take antihyperglycemic medications
• Participants with known atherosclerotic disease: coronary artery disease, peripheral artery disease or history of cerebrovascular disease (stroke or Transient Ischemic Attack (TIA), carotid stenosis)
• Participants with known systemic inflammatory conditions (including but not limited to: inflammatory arthritis, vasculitides, inflammatory bowel diseases, cancer within past 5 years, Hashimoto's thyroiditis)
• Participants currently taking any anti-inflammatory medications or medications that target inflammatory cytokines
• Pregnancy: because blood glucose problems during pregnancy require intensive monitoring and lifestyle changes to protect the mother and fetus
• Participants with known or suspected Covid-19 in the prior 30 days
• Participants with post-covid sequelae (a.k.a "Long covid")
• Participants who are already utilizing HEPA filtration (PAC or within HVAC) in bedrooms

The de-identified participant data from the final research dataset used in the published manuscript will be shared upon reasonable request beginning 9 months and ending 36 months following article publication or as required by a condition of awards and agreements supporting the research provided the investigator who proposes to use the data executes a data use agreement with NYU Langone Health. Requests may be directed to: Sharine.Wittkopp@nyulangone.org. The protocol and statistical analysis plan will be made available on Clinicaltrials.gov only as required by federal regulation or as a condition of awards and agreements supporting the research

Beginning 9 months and ending 36 months following article publication or as required by a condition of awards and agreements supporting the research.

The investigator who proposed to use the data will be provided access upon reasonable request. Requests should be directed to Sharine.Wittkopp@nyulangone.org. To gain access, data requestors will need to sign a data access agreement.